The present invention relates to a battery recharging device and method which tests a battery to determine if it should not be recharged. More specifically, the present invention relates to an automatic battery detection system and method for use with an electronic device, such as wireless two-way communication devices, pagers, integrated email devices and cellular phones, powered by a battery. The electronic device is electrically connected to an associated recharging device to test the battery. This testing is performed by a controller that determines if the device includes a battery that should not be recharged. If the testing does not indicate that the battery should not be recharged, then a recharging operation is performed.
Generally, wireless transceivers, such as those used in radios, cell phones, pagers, etc., are powered by rechargeable batteries. Most commercially available rechargeable cells, such as Nickel Metal Hydride (NiMH) or Nickel-Cadmium (NiCd) cells, are recharged by an external charger (i.e., the user removes the batteries from the device and recharges them in the external charger). However, some devices recharge the batteries without removing them from the device.
To recharge the battery without removing it from the device, the type of cell within the battery must first be determined by the recharging device. Usually, the rechargeable batteries are modified to facilitate cell-type detection. This modification of the battery typically is done by adding a third terminal to the battery where detection is performed by a detector that measures the batteries characteristics through an electrical contact with the third terminal.
Another method of in-unit cell detection is performed through some form of user input such as a mechanical switch with an arrow that is lined up with one or more markings on the device. These markings represent chemical symbols or words that indicate the cell-type of the battery to the device charging the cell.
When recharging a battery though a charging cradle it is necessary to first test the battery to reduce the possibility of damaging either the device or the battery. If a device having a non-rechargeable battery is placed in the charging cradle during a recharging operation both the battery and the device could be damaged. Further, if a rechargeable battery is recharged when it is already almost fully charged, the number of charging cycles is lowered and the lifetime of the battery is drastically reduced.
According to the present invention, a recharging device, which may for example be a charging cradle, is electrically connected to an electronic device powered by a battery. A controller performs a method of internal-device battery cell detection, i.e., distinguishing between NiMH/NiCd and other types of cells in the battery, before recharging the battery. A method determines the cell chemistry without any modifications to the battery and/or without any user input by performing a plurality of tests. The tests may include a Battery Voltage Test, an Internal Resistance (IR) Test, and a Timed Voltage Test. The tests are preferably executed in a predetermined order. The testing is performed through a combination of hardware and software which may be in the charging cradle.
One advantage of the present invention is that alkaline, lithium, rechargeable alkaline, and carbon-zinc cells are detected and not recharged while the battery remains in the device without modifying the battery, which protects the device from being damaged.
Another advantage of the present invention is that damaged NiNH and NiCd cells are detected and not recharged while the battery remains in the device without modifying the battery, which protects the device from being damaged.
Still another advantage of the present invention is that close to fully charged NiMH and NiCd cells are detected and not recharged while the battery remains in the device without modifying the battery, which extends the life of the battery and prevents overcharging of the battery.
Another advantage of the present invention is that the detection process may be conducted without requiring input from a user.
These are just a few of the many advantages of the invention, which is described in more detail below in terms of a preferred embodiment. As will be appreciated, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description of the preferred embodiments are to be regarded as illustrative in nature and not restrictive.